As recording became more computer-based, equipment vendors tried to build a range of interface devices to serve the various niches in the market. As a result, users — faced with a glut of choices — had to develop a strategy for matching the interface with the application. Here’s a way to categorize the basic choices.

First of all, the user should acknowledge the key functionality of an interface. Essentially, the interface should accept analog microphone and line-level signals and convert them to digital data. The data is then processed by the computer or stored on memory.

In addition, most interfaces also reverse the course and accept digital audio signals from the computer and convert them back to analog signals. This signal is used for headphones, studio monitors or other processing gear. That’s the basic principle.

Choice is not about audio quality

It should also be known that sound quality is no longer an issue that differentiates the latest models of audio interfaces. The least expensive devices, when used properly, deliver excellent audio quality. There might be minute differences in the audio, but nothing that really matters when choosing an interface.

At this point — you guessed it — things get more complicated. Beyond basic functionality, incredibly sophisticated features are available. Choices include; multiple digital I/O formats, MIDI, monitor control capabilities and flexible routing options.

Also, onboard digital signal processing (DSP) for latency-free monitoring or processing signals is often used in more expensive interfaces. If your requirements call for a number of plug-ins, a DSP accelerator can be a useful accessory because it takes the processing weight off of the computer.

What is the application?

So back to the key question: which interface is right for your application? 

Like most decisions regarding technical infrastructures, a complete assessment of your workflow comes first. It’s a matter of having slightly more capability than you need, but not having too much. More capability than you need can slow the whole process down, due to both complexity in the workflow and drain on the computer’s processing power.

First of all, what are you doing? Do you need to record multichannel audio in the field, narration or interviews, general broadcast audio production or perhaps recording music? Each of these applications helps determine the right combination of hardware and software needed for the job. Start by defining the job.

Next, the format and age of the computer being used with the interface is important. Do you want USB, USB-C, Thunderbolt, FireWire or some other connection format between the interface and the computer? This can narrow your choices quickly. The rule of thumb is to use the fastest format you can afford. If you have a new Mac, choose Thunderbolt because it is the fastest and will deliver more bang for the buck. It’s on most new Macs.

Voice or music and # of channels

Another major consideration is how many channels are you recording and where are you recording them? If you’re doing multichannel field recording, consider the iOS format on an iPad. If you’re working at a fixed location, go with Mac or a PC. Determine how many mics you will use at one time (and then add a couple of more channels to be safe). Be sure to account for phantom power in the interface.

If you are doing music production, it is totally different than other kinds of work. Consider the processing you will need. Will you need compressors, EQ and other effects in your workflow, or will it be saved for post? How many headphone feeds are needed? How many sets of monitors? Note the big difference in required features between music and other forms of audio production.

Formats and cost

Also consider the formats and connectors in your workflow. You’ll probably have XLR connectors for mics and ¼-inch phone jacks for line level inputs. But what else? Perhaps RCA, 3.5mm mini, S/PDIF, AES or ADAT optical digital ins and outs. Perhaps MIDI, Dante, AVB or RedNet or connections to another network. Map it all out in advance.

As you probably have found, the sky can be the cost limit with audio interfaces. Excellent quality single channel interfaces can be found for $99 and range in cost upwards into the thousands of dollars. Very simply, the cost depends on your needs.

However, before considering cost, narrow your choices to fit your requirements. Never start with price as the first consideration. That’s a sure way to buy the wrong interface. Don’t buy features you don’t need. It’s a waste and will definitely slow you down.

The good news is that for very little money, anyone can buy a totally professional-quality digital audio interface to use with nearly any computer. The bigger problem is not knowing how to use it and what to do with it. That’s another problem, for another article.